WO2005051840A1 - Lithium metal phosphates, method for producing the same and use thereof as electrode material - Google Patents

Abstract

The invention relates to a method for producing a compound of formula LiMPO4, in which M represents at least one metal of the first transition series, said method comprising the following steps: a) production of a precursor mixture containing at least one Li<+> source, at least one M<2+> source and at least one PO4<3-> source in order to obtain a precipitate and produce a precursor suspension; b) treatment of the precursor mixture and/or precursor suspension by dispersion or grinding, until the D90 value of the particles in the precursor suspension is less than 50 mu m; and c) extraction of LiMPO4 from the precursor suspension obtained in step b), preferably by conversion under hydrothermal conditions. The resultant material exhibits particularly advantageous particle-size distributions and electrochemical characteristics when used in electrodes.

Description

LITHIUM METAL PHOSPHATEΞ, PROCESS FOR THE PRODUCTION THEREOF AND THEIR USE AS ELECTRODE MATERIALS

description

The present invention relates to a process for the production of lithium iron phosphate, the material of very small particle size and narrow particle size distribution obtainable thereafter and its use, in particular in a secondary battery.

The prior art discloses the use of synthetic lithium iron phosphate (LiFePo) as an alternative cathode material in lithium ion batteries. This was first reported in A.K. Padhi, K.S. Nanjundaswamy, J.B. Goodenough, J. Electrochem. Soc. Vol. 144 (1977), and is also disclosed, for example, in US 5,910,382.

The use of phosphates such as lithium iron phosphate as a positive electrode for secondary lithium batteries is still in

WO 02/099913 AI described, wherein for the preparation of an equimolar aqueous solution of Li ⁺ , Fe ³⁺ and P0 ₄ ^{3 "} evaporates the water and thereby a solid mixture is prepared, whereupon the solid mixture decomposes at a temperature below 500 ° C. is to produce a pure Li and Fe phosphate precursor, and then by reacting the precursor at a temperature of less than 800 ° C in a reducing atmosphere LiFeP0 powder is obtained.

Other so-called sintering methods are known from the prior art. On the one hand, disadvantages are the high material costs of the starting chemicals (for example iron oxalate). The protective gas consumption during the sintering process is also considerable and toxic by-products such as CO are formed during sintering. It has also been found that often the particle size distribution of the product is very broad and bimodal. Further preparation processes are known, for example, from WO 02/083555, EP 1 094 523 A1, US 2003/0124423 and Franger et al., Journal of Power Sources 119-121 (2003), pages 252-257.

Also, JP 2002-151082 A describes lithium iron phosphate, processes for its production and a secondary battery using it. The process for producing lithium iron phosphate is characterized in that a lithium compound, a divalent iron compound and a phosphoric acid compound are mixed so that at least the molar ratio of the divalent iron ions and the phosphoric acid ions is about 1: 1, and the mixture in a temperature range of at least 100 ° C is reacted to a maximum of 200 ° C in a sealed vessel with the addition of a polar solvent and an inactive gas. The lithium iron phosphate thus obtained can then be physically comminuted. Although useful lithium iron phosphate can already be obtained by the prior art methods, the conventional production methods still have the disadvantage that it is not possible to obtain powdered lithium iron phosphate having a very small particle size and a very narrow particle size distribution.

There is therefore a great need for suitable processes for producing a lithium iron phosphate having a very small particle size and a very narrow particle size distribution, which can be incorporated well into the electrode material of a secondary battery and exhibits very good electrochemical properties there.

It was thus an object of the present invention to provide a process for production of lithium iron phosphate, which avoids the disadvantages of the prior art, and more particularly provides for electrodes of rechargeable ^batteries' suitable material.

The above object is achieved by the method according to claim 1. Advantageous or preferred developments are specified in the subclaims.

Apart from the preparation of LiFePO, the process according to the invention can also be used for the preparation of other compounds of the general empirical formula LiMPO ₄ , in which M represents at least one metal of the first transition series. Generally M is selected from at least one metal of the group consisting of Fe, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, ^'Be, Mg, Ca, Sr, Ba, Al, Zr and La. More preferably, M is selected from Fe, Mn, Co and / or Ni. Preferably, however, M comprises at least Fe. Also, M may be two or more transition metals in the compound LiMPO 4; For example, the iron in LiFePO _{4 may be} partially replaced by one or more other metals selected from the group above, e.g. B. be replaced by Zn. Particularly preferred is LiFePo. LiMPO is preferably recovered in the phase-pure form by the process according to the invention.

Thus, it has surprisingly been found according to the invention that in a process for preparing LiMPO by an intensive dispersing or grinding treatment of a precursor mixture or suspension containing at least one Li ⁺ source, at least one M ²⁺ source and at least one P0 ₄ ³ source , a very narrow particle size distribution and a very small particle size of the final product, LiMP0, can be achieved.

The use according to the invention of the dispersing or milling treatment of the precursor mixture results in intensive mixing and at the same time deagglomeration or reduction of the particle aggregates in the suspension. This is not accomplished by conventional low speed stirring.

To carry out the dispersing or milling treatment of the present invention, each the skilled person can be used as appears suitable apparatus can be produced with the sufficient shearing forces or turbulence an intensive research to micro ^'also result in a de-agglomeration or reduction in the particle aggregates in the suspension can, so that a D90 value of less than 50 microns is achieved. Preferred devices include dispersants (with or without pump rotors), Ultraturrax, mills such as colloid mills or Manton-Gaulin mills, intensive mixers, centrifugal pumps, in-line mixers, mixing nozzles such as injector nozzles or ultrasonic devices. Such devices as such are known to the person skilled in the art. The adjustments required to obtain the desired effect on the average particle size in the precursor suspension (see above) can be determined by routine experimentation, depending on the type of device.

In many cases, a power input into the precursor suspension within the dispersing or milling treatment according to the invention will be at least 5 kW / m ^{3 of} the mixture or suspension to be treated, in particular at least 7 kW / m ³ . This power input can be determined in a known manner depending on the device, eg when using an Ultra-Turrax stirrer with the formula P = 2'irn "M, where M represents the torque and n the speed.

According to a further preferred embodiment of the invention, the energy input into the precursor suspension in the dispersing or milling treatment according to the invention will be at least 5 kWh / m ^{3 of} the mixture or suspension to be treated, in particular at least 7 kWh / m ³ . In this case, preferably, but not necessarily, the above values for the power input are met.

Surprisingly, it has also been found that comminution of the finished LiMP0 ₄ instead of the dispersion or milling treatment in the preparation according to the invention does not lead to the corresponding advantageous properties of the LiFeP0 ₄ powder, even if it is attempted to obtain comparable particle size distributions.

It is believed, without the invention being limited to this theoretical mechanism, that in the dispersing or dispersing process Milling treatment according to the invention, in particular, the initially formed in the preparation of the mixed suspension large Kristallagglo be erate prevented, or at least be reduced after the formation. These crystal agglomerates may also be (partially) attributable to phosphates of Li ⁺ and M ²⁺ as intermediates which, depending on the concentration, may lead to an increase in viscosity due to the formation of larger crystal platelets or agglomerates. According to a particularly preferred embodiment of the invention can thus be used for the dispersion of the precursor mixture or suspension also such devices whose high mixing action (or shearing) sufficient to prevent the formation of large crystallites or crystallite agglomerates in the mixture or suspension and at the same time to lead to a high rate of nucleation. Non-limiting examples of suitable devices have already been mentioned above.

The mentioned crystal aggregates or crystal platelets can also be formed by precipitation of a defined precursor (precursor) from a soluble Li ⁺ source, a soluble M ²⁺ source and the (soluble) P0 ^{3 ~} source. In the example of the invention below, for example, an aqueous solution of an Fe ²⁺ source, in particular an aqueous solution of iron (II) sulfate heptahydrate, FeS0 ₄ · 7H ₂ O, and a liquid P0 ₄ ^{3 ~} source, in particular 85% iger phosphoric acid, presented, and with slow addition of an aqueous Li ⁺ source, in particular an aqueous LiOH solution, a fresh precipitate of Vivianit (Fe ₃ (P0) ₂ hydrate) like. It is preferable in this case for the dispersing or grinding treatment to prevent or reduce the formation of large crystal platelets or crystal agglomerates already from the beginning of the first crystal formation until the conclusion of the precipitation. Before a subsequent preferred Hydrothermal treatment is then using the dispersing or milling unit, a homogeneous precursor mixture or suspension, preferably with a solid content containing Vivianit (optionally impregnated with Li ⁺ ions), lithium phosphate and / or iron hydroxides before. This intermediate (s) need not be isolated. Preferably, the combination and / or the precipitation of the precursor mixture or suspension can already be carried out in the hydrothermal vessel (one-pot process).

The dispersing or grinding treatment according to the invention thus ensures that the precipitation proceeds very homogeneously and a homogeneous mixture of many small, approximately equal-sized crystal nuclei is formed. These crystal nuclei can then be reacted with a very narrow particle size distribution, in particular during a subsequent hydrothermal treatment, to give very uniformly grown crystals of the end product LiMPO ₄ . In principle, in the context of the invention instead of the hydrothermal treatment also, optionally after separation of the mother liquor, for example by filtration and / or centrifuging, drying and optionally sintering of the precipitate from the precursor mixture according to the invention dispersing or grinding treatment possible. However, the hydrothermal treatment is preferred and gives the best results.

In order to achieve the desired effect, the dispersing or milling treatment according to the invention can therefore preferably be used before or during the precipitation of a precipitate from the precursor mixture in order to prevent the formation of large crystal nuclei or agglomerates or to comminute and homogenize them. In this case, a D90 value of the particles in the suspension of less than 50 microns is to be achieved. It is preferred a D90 value of the particles in the precursor suspension of not more than 25 μm, in particular not more than 20 μm, particularly preferably not more than 15 μm, since the best properties of the finished product have been observed.

According to one embodiment of the invention, the dispersing or milling treatment according to the invention can also be used after precipitation of a precipitate from the precursor mixture, provided that the above mentioned D90 value is reached.

It has also surprisingly been found that the dispersing or grinding treatment according to the invention should preferably take place before the final conversion to the lithium iron phosphate, in particular before completion of a subsequent to the precipitation of the precursor mixture hydrothermal treatment in order to achieve optimum results. However, as a dispersing or grinding treatment according to the invention, both a treatment of a precursor mixture before and during a hydrothermal treatment is considered.

A significant advantage of the method according to the invention is that the particle size distribution of the produced LiMP0 ₄ can be controlled particularly well reproducible, and thus the good electrochemical properties can be stably maintained without great fluctuations.

In the present invention, the choice of the Li ⁺ source, the M ²⁺ source and the P0 ^{3 "} source is in principle not restricted, and all starting materials which are familiar or suitable for the person skilled in the art can be used. divalent compounds of M and phosphoric acid compounds suitably combined as synthesis basic materials are used. Preference is given to soluble salts or compounds of Li and M and liquid or soluble P04 sources. As examples of suitable lithium compounds, there may be mentioned, without limitation, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium carbonate, lithium hydroxide or lithium phosphate, among others. Particularly preferred is LiOH.

As examples of divalent compounds of M, here for example with M = Fe, without limitation, i.a. Iron fluoride, iron chloride, iron bromide, iron iodide, iron sulfate, iron phosphate, iron nitrate, organyl salts of iron such as iron oxalate or iron acetate. Iron sulfate is particularly preferred. If M is a metal other than Fe, the analog connections can be used.

As examples of phosphoric acid compounds, without limitation, i.a. Orthophosphoric acid, metaphosphoric acid, phosphoric acid, triphosphoric acid, tetraphosphoric acid, hydrogen phosphates or dihydrogen phosphates such as ammonium phosphate or onium dihydrogen phosphate, lithium phosphate or iron phosphate or any mixtures thereof. Phosphoric acid is particularly preferred.

When LiOH is used as the Li ⁺ source and phosphoric acid as the P0 ₄ ^{3 "} source, addition of LiOH can neutralize the phosphoric acid and thus initiate the precipitation in the precursor mixture.

According to the invention, any liquid or fluid mixture comprising at least one Li ⁺ source, at least one M ²⁺ source and at least one P0 ₄ ³ source is regarded as the precursor mixture. As a precursor suspension, any liquid or fluid precursor mixture is considered according to the invention after at least partial precipitation of a precipitate. The precipitate may contain LiMP0 ₄ or intermediates.

In general, the precursor mixture will contain a solvent, in particular a polar solvent. As a polar solvent, for example, water, methanol, ethanol, 2-propanol, ethylene glycol, propylene glycol, acetone, cyclohexanone, 2-methylpyrrolidone, ethyl methyl ketone, 2-Ethoxiethanol, propylene carbonate, ethylene carbonate, dimethyl carbonate, Dimethylfόrmamid or dimethyl sulfoxide or mixtures thereof may be mentioned. Water is preferred as a solvent. The preferred wet precipitation of the LiMP0 ₄ from aqueous solution can then take place according to the invention. According to the invention, it is therefore possible to start from the known starting materials and solutions or suspensions known to the person skilled in the art for the preparation of the LiMPO ₄ . In particular, the formulations and processes known for wet precipitation from solutions can be used, the dispersing or grinding treatment being additionally provided according to the invention. The temperature in the preparation of the precursor mixture or the combination of the at least one Li ⁺ source, the at least one M ²⁺ source and / or the at least one P0 ₄ ^{3 "} source is preferably in the range between about 20 and 80 ° C , in particular between 25 and 60 ° C, selected.

According to a preferred embodiment of the method according to the invention, there is no direct evaporation or drying of the precursor mixture or precursor suspension. Also, according to a preferred embodiment, no sintering of the precursor mixture or precursor suspension takes place, as this may adversely affect the properties of the final product obtained. Rather, it has surprisingly been found that the best results are obtained by a hydrothermal treatment of the precursor mixture or precursor suspension and subsequent drying and optionally sintering of the fully reacted LiFePO.

Under a reaction of the precursor mixture under hydrothermal conditions. In the context of the present invention, any treatment at a temperature above room temperature and a vapor pressure above 1 bar is considered. The hydrothermal treatment per se can be carried out in a manner known and familiar to the person skilled in the art. Preferably, in the hydrothermal conditions temperatures between 100 to 250 ° C, in particular 100 to 180 ° C and a pressure of 1 bar to 40 bar, in particular 1 bar to 10 bar steam pressure used. A possible hydrothermal process is described for example in JP 2002-151082, the relevant disclosure of which is incorporated herein by reference. In one embodiment, the precursor mixture is reacted in a sealed or pressure-resistant vessel. The reaction is preferably carried out in an inert or inert gas atmosphere. Suitable inert gases are, for example, nitrogen, argon, carbon dioxide, carbon monoxide or mixtures thereof. The hydrothermal treatment can be carried out for example for 0.5 to 15 hours, in particular for 3 to 11 hours. Only as a non-limiting example, the following specific conditions can be selected: 1.5 h heating of '50 ° C (temperature of the precursor mixture) to 160 ° C, 10 h hydrothermal treatment at 160 ° C, 3 h cooling from 160 ° C to 30 ° C.

According to a preferred embodiment of the invention, first in an aqueous medium, the M ²⁺ source and the P04 ^3_ source, especially under an inert gas atmosphere, mixed and then, preferably again under an inert gas atmosphere, the Li source added. At the latest with the onset of the precipitation with increasing neutralization of the precursor mixture, the dispersing or grinding treatment is then started and then the reaction is carried out under hydrothermal conditions. According to one embodiment of the invention, a separation of the LiMPO from the suspension, eg via filtration and / or centrifugation, can follow the hydrothermal treatment. Furthermore, according to one embodiment of the invention, the separated LiMPO can be washed, in particular with water, in order to reduce or remove the salt load. Drying and / or sintering of the LiMP0 ₄ , in particular under a protective gas or inert atmosphere, can likewise follow the hydrothermal treatment. Careful drying / drying • is usually required for the electrochemical quality of the final product, since even slight traces of moisture in the electrochemical application of the material in Li-accumulators or Li-batteries can cause problems such as a decomposition of the conductive salt LiPF ₆ . Sintering can be done optionally.

The drying of the LiMP0 ₄ can be carried out over a wide temperature range of about 50 to 750 ° C,. the drying temperature also depends on economic considerations. If the preparation of the LiMP0 _{4 is carried out} in the absence of a carbonaceous or electron-conductive substance or a precursor thereof (see below), in most cases a drying between about 50 and 350 ° C, for example for 3 h at 250 ° C under Use of nitrogen 5.0, vacuum or forming gas, be sufficient. As far as the production of the LiMP0 ₄ in the presence of a carbonaceous or electron-conductive substance or a precursor thereof (see below) is carried out to effect carbon precoating, usually a higher drying temperature, usually above 500 or 700 ° C, selected. In particular, sintering may be carried out, wherein, for example, it may be heated at about 750 ° C for 3 hours using nitrogen 5.0. Only at sufficiently high temperatures is the desired conductive coating of the carbon-containing or electron-conductive substance obtained.

According to a preferred embodiment of the invention, the components of the precursor mixture are present in the following stoichiometric ratio: a. 1 mol of Fe ²⁺ : 1 mol of P0 ₄ ^{3 ~} : 1 mol of Li * (1: 1: 1) b. 1 mol of Fe ²⁺ : 1 mol of P0 ₄ ^{3 ~} : 3 mol of Li * (1: 1: 3) c. every mixing ratio between a and b

Preferably, at least the molar ratio of M ²⁺ iron ions to P0 ₄ ^{3 ~} is about 1: 1. The above stoichiometric ratios are also preferred for economic reasons, but not necessarily. Especially in the hydrothermal process, LiMP0 _{4 is formed} as the thermodynamically most stable phase preferably, and deviations from the above-mentioned conditions for influencing the precipitation or morphology properties may even be intended in individual cases. As a rule, deviations of 20%, at least about 10% of the above stoichiometric ratios can be tolerated.

The hydrothermal process also offers advantages in terms of a greatly reduced shielding gas requirement compared to a alternatively possible sintering process from a dry powder premix or precursor mixture. In addition, it was surprisingly found that the particle morphology and particle size distribution can be controlled much more targeted than in a pure sintering process.

At high charge-discharge rates (high charge / discharge currents), too large LiFeP0 particles lead to a kinetically controlled limitation. The capacitance which can be taken from an accumulator, ie the lithium ions can no longer move fast enough through the boundary layer LiFeP0 ₄ / FeP0 during discharge. the specific capacity of the electrode drops sharply at high charge / discharge rates. However, for a commercial use of the lithium iron phosphate, a sufficient specific capacity is also important at high charge / discharge currents.

The investigations by the inventors have also shown that it is not possible to achieve neither the same small particle size and narrow particle size distribution nor the outstanding electrochemical properties by mere post-milling and / or screening of the finished LiMP0 ₄ prepared without the dispersing or grinding treatment according to the invention. This also applies to LiMPO ₄ , which has been prepared only by direct sintering of a powder precursor mixture. It is believed that this is due to _the uniform ^'and small crystal nuclei which the invention will be produced by the dispersing or milling treatment in accordance with the reaction and ₄ product are based on the finished LiMP0. The resulting finely divided and uniform particle size also has a positive effect in the case of drying or sintering of the LiMPO produced by the process according to the invention. Another aspect of the present invention therefore relates to LiMP0 ₄ , which is obtainable by the method described above. This material preferably has a D ₉₀ value of the particles of not more than 25 μm, in particular not more than 20 μm, particularly preferably not more than 15 μm. The average (average) particle size (D50 value) is less than 0.8 μm, preferably less than 0.7 μm, in particular less than 0.6 μm, particularly preferably less than 0.5 μm. The particle size distribution is preferably at least substantially a normal distribution (monomodal). The DIO value in one embodiment is less than 0.35 μm, preferably less than 0.40 μm, but may also be higher for narrow particle size distributions, depending on the D90 value. The D90 value is preferably less than 3.0 μm, preferably less than 2.5 μm, in particular less than 2.0 μm.

As mentioned above, the particle size distribution of the LiMP0 ₄ according to the invention is preferably very narrow, and according to a particularly preferred embodiment, the difference between the D90 value and the DIO value is not more than 2 μm, preferably not more than 1.5 μm, in particular not is more than 1 μm, more preferably not more than 0.5 μm.

It has surprisingly been found that the advantages of the LiMP0 ₄ according to the invention described above also offer particular advantages in the subsequent processing with other components, for example of carbonaceous materials in the production of electrode materials. Thus, according to the invention, the LiMPO, owing to its particular particle size distribution, as defined herein, enables better and easier processing into electrode materials and a particularly intimate bond with, for example, the carbonaceous conductive materials. Another Another aspect of the present invention therefore relates to a composition, in particular electrode material, containing LiMP0 ₄ as defined herein.

Another aspect of the present invention relates to the use of a LiMP0 ₄ material as defined above in a lithium secondary battery or a secondary (rechargeable) Li battery as the electrode material. Preferably, the primary particles (= crystallites) of the finished LiMP0 ₄ product in SEM images are largely uniform in size and morphology. By contrast, LiMPO ₄ produced by the process according to the invention have non-uniformly large primary particles or nonuniform crystal morphologies.

According to a preferred embodiment of the invention, the preparation or precipitation of the precursor mixture and / or the reaction takes place under hydrothermal conditions in the presence of further components, in particular an electron-conductive substance. This may preferably be a carbonaceous solid such as coal, in particular conductive carbon or carbon fibers. It is also possible to use a precursor of an electron-conducting substance or of the carbonaceous solid which converts to carbon particles during the drying or sintering of the LiMPO ₄ , such as a sugar compound. Further examples of suitable organic compounds are mentioned in WO02 / 083555, the relevant disclosure of which is incorporated herein by reference. Preferably, the carbon particles contained in the final LiMP0 ₄ product are homogeneously distributed. According to a particularly preferred embodiment of the invention, the carbonaceous solid used is used as a crystallization seed in the reaction of the precursor mixture. In principle, however, any method familiar to the person skilled in the art for introducing carbon or carbonaceous, electrically conductive material or for mixing with other components is suitable. An intensive mixing or grinding of the finished LiMP0 ₄ with at least one carbonaceous solid such as carbon is possible. Further possible methods are the deposition of carbon particles onto the surface of the LiMP0 ₄ particles in an aqueous or nonaqueous suspension or the pyrolysis of a mixture of LiMP0 ₄ powder and a carbon precursor material. The carbon-containing LiMPOi thus obtained, for example, generally contains up to 10% by weight, preferably up to 5% by weight, particularly preferably up to 2.5% by weight, of carbon, based on the LiMPO ₄ .

Technically, a pyrolysis process is preferred in which at least one carbon precursor material, preferably a carbohydrate, such as sugar or cellulose and particularly preferably lactose, is mixed with the LiMP0 ₄ powder according to the invention, eg. B. by kneading, with water can be added as an aid. According to a technically particularly preferred embodiment, the carbon precursor material is added to the still undried wet LiMP0 ₄ filter cake. Subsequently, the mixture of inventive LiMP0 powder and carbon precursor material is dried on inert gas, in air or in vacuo at temperatures of preferably 50 ° C to 200 ° C and inert gas such. B. nitrogen 5.0 or argon to a tempera ture between eg 500 ° C and 1000 ° C, preferably heated between 700 ° C and 800 ° C, wherein the carbon precursor material is pyrolyzed to coal. Subsequently, preferably a Mahloder Deagglomerationsbehandlung. According to a further preferred embodiment of the invention, the BET surface area of the LiMPO _{4 used} is more than about 3.5 m ² / g, in particular more than about 4 m ² / g, particularly preferably more than 5 m ² / g, more than 10 m ² / g or even more than 15m ² / g, determined according to DIN 66131 (multipoint determination).

An improvement of the properties of the LiFeP0 ₄ by a pre-coating with carbon is also described in: Ravet et al., Abstract no. 127, 196 ^th ECS Meeting, Honolulu, HI, Oct. 17-22 (1999).

The carbon content also improves the processability of the LiMP04 powder to battery electrodes by changing the surface properties and / or improves the electrical connection in the battery electrode.

Alternatively, a significant improvement in the electronic conductivity by targeted doping with Mg ²⁺ , Al ³⁺ , Ti ⁴⁺ , Zr ⁺ , Nb ⁵⁺ , W ^{6+ be} possible (SY Chung, JT Bloking, YM Chiang, Nature, Vol. 1, October 2002, 123).

A further aspect of the invention relates to a Li-accumulator or a Li-secondary battery containing the inventive, given carbon-containing, LiMP0 _4th As such, the secondary battery (lithium ion secondary battery) can be manufactured in a manner known per se, for example, as set forth below and described in JP 2002-151082. Incidentally, the lithium iron phosphate of the present invention obtained as above is used at least as a part of the material for the positive pole of the secondary battery. In this case, mixing of the lithium iron phosphate of the present invention with, if necessary, electrochemical electrically conductive additives and a binder according to a conventional method for producing the positive electrode of a secondary battery. The secondary battery is then made of this positive electrode, and a commonly used negative electrode material such as metallic lithium or a layered carbon compound such as graphite, further from a commonly used nonaqueous electrolytic solution such as propylene carbonate or ethylene carbonate or the like Lithium salt such as LiBF ₄ or LIPF _{Θ is} dissolved, prepared as main components.

Determination of particle size distribution:

The particle size distributions for the precursor suspensions and the generated LiMP0 ₄ are determined by the light scattering method using commercial equipment. This method is known to the person skilled in the art, and reference is also made to the disclosure in JP 2002-151082 and WO 02/083555 and reference is made. In the present case, the particle size distributions were determined with the aid of a laser diffraction meter (on Mastersizer S, Malvern Instruments GmbH, Herrenberg, DE) and the manufacturer's software (version 2.19) with a Malvern S all Volume Sample Dispersion Unit, DIF 2002 as measuring unit. The following measuring conditions were selected: Compressed ranks; acti- ve beam length 2.4 mm; Measuring range: 300 RF; 0.05 to 900μm. The sample preparation and measurement was carried out according to the manufacturer's instructions. The D90 value indicates the value at which 90% of the particles in the measured sample have a smaller or equal particle diameter. Accordingly, the D50 value or the DIO value indicate the value at. 50% or 10% of the particles in the measured sample have a smaller or the same particle diameter.

According to a particularly preferred embodiment of the invention, the values given in the present description for the DIO values, the D50 values, the D90 values and the difference of the D90 and DIO values relative to the volume fraction of the respective particles in the total volume apply. Thereafter, the hereinabove mentioned D10, D50 and D90 values according to this embodiment of the present invention indicate those values at which 10% by volume, 50% by volume and 90% by volume, respectively. of the particles in the measured sample have a smaller or the same particle diameter. In keeping with these values, particularly advantageous materials are provided according to the invention and negative influences of relatively coarse particles (with a relatively larger volume fraction) on the processability and the electrochemical product properties are avoided. The values given in the present specification for the DIO values, the D50 values, the D90 values and the difference between the D90 and the DIO values, both based on percent and percent by volume of the particles, are particularly preferred.

For compositions (eg, electrode materials) containing other components in addition to the LiMP0 ₄ , especially in carbonaceous compositions, the above light scattering method can lead to misleading results, since the LiMP0 ₄ particles are affected by the additional (eg, carbonaceous) Material may be connected to larger agglomerates. However, the particle size distribution of LiMP0 ₄ in such compositions can be determined from SEM images as follows:

A small amount of the powder sample is suspended in acetone and sonicated for 10 minutes. Immediately thereafter, a few drops of the suspension are dropped onto a sample plate of a scanning electron microscope (SEM). The solids concentration of the suspension and the number of drops are so dimensioned that a substantially single-layered layer of powder particles (the term "particles" is used as a synonym of "particles") is formed on the support to prevent mutual concealment of the powder particles prevent. The dripping must be done quickly before the particles can separate by sedimentation according to the size. After drying in air, the sample is transferred to the measuring chamber of the SEM. In the present example, it is a device of the type LEO 1530, which is operated with a field emission electrode at 1, 5 kV excitation voltage and a sample distance of 4 mm. From the sample, at least 20 randomized cropping magnifications are recorded at a magnification factor of 20,000. These are each printed on a DIN A4 sheet together with the enlargement scale displayed. If possible, at least 10 freely visible LiMP0 ₄ particles constituting the powder particles together with the carbonaceous material are randomly selected on each of the at least 20 leaves, the boundary of the LiMP0 ₄ particles being defined by the absence of solid, direct adhesion bridges , By contrast, bridging by carbon material is counted as particle boundary. From each of these selected LiMP0 ₄ particles, the longest and shortest axis in projection is measured off with a ruler. and converted to the real particle dimensions based on the scale ratio. For each measured LiMP0 ₄ particle, the arithmetic mean ^' of the longest and the shortest axis is defined as the particle diameter. Subsequently, the measured LiMP0 ₄ particles are divided into size classes in analogy to the light scattering measurement. Applying the number of respective associated LiMP0 ₄ particles over the size class, one obtains the differential particle size distribution based on the number of particles. If the numbers of particles are continuously added up from the small to the large particle classes, one obtains the cumulated particle size distribution, from which D10, D50 and D90 can be read directly on the size axis.

The method described also applies to L1MPO ₄ -containing battery electrodes. In this case, however, a fresh cut ^"or fracture surface of the electrode attached instead of a powder sample on the sample carrier and analyzed in the SEM.

The invention will now be explained in more detail with reference to the following non-limiting examples. The attached figures show:

Fig. 1 (by volume) the particle size distribution a ^'s LiMP0 according to the invention prepared according to Example 1;

FIG. 2 shows the particle size distribution (based on volume) of a LiMPO ₄ according to Example 2 not according to the invention; FIG.

3 shows the particle size distribution (by volume) of an L1MPO ₄ prepared according to the invention in accordance with Example 3. Examples:

Example 1: Preparation of LiFePQ by a process according to the invention including hydrothermal treatment

reaction equation

FeS0 ₄ ^• 7H ₂ 0 + H ₃ P0 ₄ + 3 LiOH • H ₂ 0 → LiFePO ₄ + Li ₂ S0 ₄ + 11 H ₂ 0

LiFeP0 ₄ can be stored as a finished product at room temperature in air without oxidation.

In the preparation of LiFeP0 ₄ according to the stated reaction equation is to be noted that the LiFe ^{ι: ι:} P0 _{4 is} precipitated from an aqueous Fe ^{ι: r} -Precursorlösung. The reaction and drying / sintering should therefore be carried out under protective gas or vacuum in order to avoid partial oxidation of Fe ¹¹ to Fe ¹¹¹ to form by-products such as Fe ₂ O ₃ or FePO.

Production and precipitation of a precursor mixture

417.04 g of FeSO ₄ .7H ₂ O are dissolved in about 1 l of distilled water and, while stirring, 172.74 g of 85% strength phosphoric acid are added. It is then made up to 1.5 l with distilled water. The acidic solution is placed in the laboratory autoclave (volume: 1 gallon) at 400 rpm stirrer speed, the autoclave via the dip tube with about 6 - 7 bar nitrogen applied and relaxed through the vent valve again. The procedure is repeated twice. 188.82 g of lithium hydroxide LiOH • H ₂ O are dissolved in 11 distilled water.

To perform the dispersing or grinding treatment according to the present invention, a disperser (company IKA, ULTRATURRAX® UTL 25 Basic Inline with dispersing chamber DK 25.11) is connected to the autoclave between the venting valve and the bottom outlet valve. The pumping direction of the disperser is bottom outlet valve - disperser - vent valve. The disperser is started at medium power level (13500 rpm) according to the manufacturer's instructions.

Subsequently, the prepared LiOH solution is pumped via the immersion tube into the autoclave with a Prominent membrane pump (stroke 100%, 180 strokes / minute, corresponds to the highest power of the pump) and rinsed with about 500 to 600 ml of distilled water. The process takes about 20 minutes, the temperature of the resulting suspension rises to about 35 ° C. After pumping and rinsing, the suspension is heated to 50 ° C. in an autoclave. After addition of the lithium hydroxide precipitates a greenish brown precipitate.

The dispersant, which is started before the beginning of the LiOH addition, is used for a total of about 1 hour for intensive mixing or grinding of the resulting, very viscous suspension (after pumping the LiOH solution at 50 ° C.). The particle size was then at D90 = 13.2 microns. The volume-related D90 value was corresponding.

The following procedure can be used to measure the particle sizes in the precursor suspension: With reference to the method for determining the particle size before the examples, (Distribution) are suspended 20 to 40 mg of the suspension in 15 ml of water and dispersed for 5 min with an ultrasonic finger (rated power 25 watts, 60% power). It is then measured immediately in the measuring unit. The correct setting of the sample quantity can be checked in each case on the basis of the display on the measuring device (green measuring range).

The use of a dispersant causes an intensive mixing and deagglomeration of the precipitated viscous premix. During the precipitation and crystallization of the precursor suspension occurring during this process, the premilling or intensive mixing in the disperser produces a homogeneous mixture of many small, approximately equal sized, crystal nuclei. These crystal nuclei crystallize in the subsequent hydrothermal treatment (see below) to very uniformly grown crystals of the final product LiFeP0 with a very narrow particle size distribution. The power or energy input via the dispersing treatment was more than 7 kW / m ³ or more than 7 kWh / m ^{3 of} the treated precursor mixture / suspension.

Hydrothermal Treatment:

The freshly prepared suspension is hydrothermally treated in a laboratory autoclave. Prior to heating the suspension, the autoclave is purged with nitrogen to displace existing air from the autoclave prior to the hydrothermal process. LiFe-P0 ₄ forms from Hydrothermaltemperaturen of about 100 to 120 ° C. After the hydrothermal process, the material is filtered off with the Seitz filter and washed. In detail:

After switching off and disconnecting the dispersant, the batch is heated to 160 ° C in 1.5 hours and a hydrothermal treatment carried out at 160 ° C for 10 hours. It is then cooled to 30 ° C in 3 hours.

Thereafter, the LiFeP0 ₄ can be dried without visible oxidation in air or in a drying oven, for example at mild temperatures (40 ° C).

However, it may also be a further processing of the material obtained as described above:

Filtration of lithium iron phosphate LiFeP0 ₄

After the hydrothermal treatment, the cooled suspension (max 30 ° C) is pumped under a nitrogen atmosphere through the bottom drain valve of the autoclave into a pressure filter (so-called "Seitz filter"), where the Prominent diaphragm pump is adjusted so that a pressure of 5 bar The filter cake is washed with distilled water until the conductivity of the wash water falls below 200 μS / c.

Drying and deagglomeration of lithium iron phosphate LiFeP0 ₄

The filter cake is pre-dried in a vacuum oven at 70 ° C overnight to a residual moisture content below 5% and then in, a protective gas oven ("Linn KS 80-S") under a Formiergasstrom (90% N ₂ /10% - H ₂ ) of 2001 / h to a residual moisture content of <0.5% at 250 ° C. Subsequently, the LiFeP0 ₄ is deagglomerated in a laboratory rotor mill ("Fritsch Pulverisette 14") with a 0.08 mm sieve.

The resulting typical particle size distribution of the finished LiFeP0 ₄ (with dispersant treatment, after hydrothermal treatment, drying and deagglomeration as described above) can be seen from FIG. To illustrate the advantageous particle size distribution and the absence of interfering larger particles in the products of the invention, the volume-related data are shown. The values relating to the particle fraction (%) were as follows: D50 value less than 0.5 μm; DIO value less than 0.35 μm; D90 value less than 2.0 μm; Difference between the D90 value and the DIO value less than 1.5 μm.

To measure the particle sizes in a powdery sample can proceed as follows: With reference to the specified before the examples method for determining the particle size (distribution) 20 to 40 mg of the powder sample are suspended in 15 ml of water and 5 min with an ultrasonic finger (rated power 25 watts, 60% power). It is then measured immediately in the measuring unit. The correct setting of the sample quantity can be checked in each case on the basis of the display on the measuring device (green measuring range).

Example 2 Preparation of LiFePQ ₄ Without Dispersant Treatment (Comparison)

For comparison, LiFePO ₄ was prepared according to the same synthesis procedure as described in Example 1, but without using the dispersant according to the invention. It was under otherwise the same reaction conditions a much broader particle. size distribution obtained with a larger proportion of intergrown agglomerate. Without the use of a dispersant, the Dgo value (based on volume fraction or particle number) was more than 200 μm after addition of the LiOH solution. The significantly higher phase purity of the LiFeP0 ₄ The particle size distribution of the finished LiFePO (after hydrothermal treatment, drying and deagglomeration) is shown in FIG. To illustrate the presence of interfering larger particles, the volume-related data are shown. The D50 value based on the particle fraction (%) was more than 0.8 μm.

Also, a LiFePO ₄ produced according to US2003 / 0124423, page 10, paragraph [0015], despite intensive grinding with a mortar, could not be brought to the particle size distribution of the products according to the invention; no D50 value less than 0.8 μm and no difference of D90 and D10 values of 2 μm or less could be achieved.

Example 3: Preparation of LiFePQ ₄ by a process according to the invention including hydrothermal treatment

It was prepared as described LiFeP0 by the same synthetic process as in Example 1 ^', however, the disperser (IKA, Ultraturrax® UTL 25 basic inline with Dispergierkam- mer DK 25.11) was operated at the highest power level. The power or energy input via the dispersing treatment was more than 10 kW / m ³ or more than 10 kWh / m ^{3 of} the treated precursor mixture / suspension. The particle size of the suspension after the dispersant treatment was Dgo ^ 10.8 microns. The volume-related D90 was slightly lower.

The hydrothermal treatment, filtration, drying and deagglomeration were carried out as indicated in Example 1. The resulting typical particle size distribution of the finished LiFePÜ ₄ is shown in FIG. 3. To illustrate the advantageous particle size distribution and the absence of interfering larger particles in the products of the invention, the volume-related data are shown. The values relating to the particle fraction (%) were as follows: D50 value less than 0.5 μm; DIO value less than 0.35 μm; D90 value less than 2.0 μm; Difference between the D90 value and the DIO value less than 1.0 μm.

In electrochemical tests, the LiFePO ₄ of the present invention prepared using the dispersant showed the comparison material prepared without using a dispersant, as well as a pure sintering method according to the prior art The material produced by the technology has the best properties, especially at high charge / discharge rates.

Example 4: Preparation of LiFePQ ₄ by a process according to the invention including hydrothermal treatment

21.894 kg FeS0 ₄ * 7H ₂ 0 are dissolved in 42 l of deionized water and slowly added with stirring 9.080 kg of 85% phosphoric acid. The acidic solution is placed in an enameled 2001 autoclave with anchor stirrer and stirred at 45 rpm. The headspace of the autoclave is purged with nitrogen before closing. The acidic solution is circulated via a centrifugal pump with approx. 5kW power consumption and with a measured flow rate of 70001 / h on average. The solution is removed via the bottom drain valve of the autoclave and fed back via a cover flange. 10.289 kg of LiOH * H0 are dissolved in 62 l of deionized water. This alkaline solution is fed via a monopump and an injector to the recirculated acidic solution on the pressure side of the centrifugal pump. This process lasts 15 minutes, with the temperature of the pumped solution rising from 18.3 ° C to 42.1 ° C. The resulting suspension is pumped further for 45 min with the centrifugal pump and stirred with the anchor stirrer at 45 rpm, with the temperature further increased to 51.1 ° C. According to the invention, the centrifugal pump with its high turbulence effect during the entire process for the formation of a finely divided suspension, wherein comparable particle size distributions as in Example 1 could be achieved. The power or energy input via the dispersing treatment was more than 7 kW / m ³ or more than 7 kWh / m ^{3 of} the treated precursor mixture / suspension. - -

After switching off and disconnecting the external devices, the autoclave is pressure-tight and heated with constant stirring at 90 rpm in 1.5 h at 160 ° C and held for 10h at this temperature. It is then cooled to 20 ° C. within 3 h and the finished LiFeP0 suspension is filtered analogously to Example 1 in the "Seitz filter". The pH of the filtrate is 7.5. It is then washed with deionized water until the filtrate has a conductivity of less than 480μS. The whitish-gray, solid and prone to bleeding filter cake is dried at 70 ° C overnight in a vacuum oven at <100mbar and deagglomerated in a laboratory rotor mill ("Fritsch Pulverisette 14") with a 0.08mm screen. The particle size distributions obtained thereafter were in the same range as given in Example 1.

Example 5: Charring of a material produced by the process according to the invention

1 kg of LiFePO ₄ powder from Examples 1 to 4 are intimately mixed with 112 g of lactose monohydrate and 330 g of deionized water and dried overnight in a vacuum drying oven at 70 ° C. and <100 mbar to a residual moisture content <5%. The brittle-hard drying product is crushed by hand and coarsely ground in a disk mill ("Fritsch Pulverisette 13") with a 1mm disk distance and transferred into stainless steel crucibles in a protective gas chamber furnace ("Linn KS 80-S"). This is heated at a nitrogen flow of 2001 / h within 3 h at 750 ° C, held for 5h at this temperature and cooled to room temperature within about 36 hours. The carbonaceous product is in a Laboratory rotor mill ("Fritsch Pulverisette 14") deagglomerated with a 0.08 mm sieve.

The SEM analysis of the particle size distribution as described before for the examples of carbonaceous masterials gave the following values: D50 value less than 0.6 μm, difference between D90 value and DIO value less than 1.5 μm.

In electrochemical tests on thin-film electrode, as described, for example, in Anderson et al. , Electrochem. And Solid State Letters 3 (2) (2000), pages 66-68 showed the carbonaceous material according to the invention (starting from the product of Examples 1, 3 and 4) compared to the comparison material prepared without using a dispersing agent as well as a pure Sintered material produced according to the prior art material the best properties, especially at high charge / discharge rates.

Claims

claims A process for the preparation of a compound of the formula LiMPO ₄ , wherein M represents at least one metal of the first transition series, comprising the following steps: a. Producing a precursor mixture containing at least one Li ⁺ source, at least one M ²⁺ source and at least one P0 ₄ ^3_ source to precipitate and thus produce a Precursorsuspension; b. Dispersing or grinding treatment of the precursor mixture .. and / or the precursor suspension until the D90 value of the particles in the precursor suspension is less than 50 μm; c. Recovery of LiMP0 ₄ from the precursor suspension obtained according to b), preferably by reaction under hydrothermal conditions. 2. The method according to claim 1, characterized in that ^" 'that the D90 value of the particles in the suspension at a maximum of 25 .mu.m, in particular a maximum of 20 • .mu.m, particularly preferably a maximum of 15 is .mu.m. 3. The method according to claim 1 or 2, characterized in that M comprises at least Fe or Fe represents. 4. The method according to any one of the preceding claims, characterized in that M comprises Fe, Mn, Co and / or Ni. 5. The method according to any one of the preceding claims, characterized in that the LiMP0 _{4 is} recovered in phase-pure form. 6. The method according to any one of the preceding claims, characterized in that the dispersing or milling treatment is used before or during the precipitation of the precursor mixture and is continued until completion of the precipitation. 7. The method according to any one of the preceding claims, characterized in that the dispersing treatment before the precipitation of the precursor mixture used to ensure a high nucleation and to prevent the formation of large crystals and crystal agglomerates. 8. The method according to any one of the preceding claims, characterized in that no evaporation takes place before the reaction of the precursor mixture or suspension under hydrothermal conditions. 9. The method according to any one of the preceding claims, characterized in that no sintering takes place before the reaction of the precursor mixture or suspension under hydrothermal conditions. 10. The method according to any one of the preceding claims, characterized in that after the reaction under hydrothermal conditions, a drying of the LiMP0 ₄ takes place. - - 11. The method according to any one of the preceding claims, characterized in that the preparation of the precursor mixture or suspension or the reaction takes place under hydrothermal conditions in the presence of at least one further component, in particular a carbonaceous or electron-conductive substance or the precursor of an electron-conductive substance. 12. The method according to any one of the preceding claims, characterized in that it is the electron-conductive substance to coal, in particular conductive carbon or carbon fibers. 13. The method according to any one of the preceding claims, characterized. in that the precursor of an electron-conducting substance is a carbon-containing substance, in particular a sugar compound. 14. The method according to any one of the preceding claims, characterized in that LiOH or LiC0 _{3 is} used as the lithium source. 15. The method according to any one of the preceding claims, characterized in that as Fe ²⁺ source is a Fe ²⁺ salt, in particular FeS0, FeCl ₂ , FeN0 ₃ , 'Fe ₃ (P0) ₂ or an organyl salt of iron is used. 16. The method according to any one of the preceding claims, characterized in, ^"that is used as P0 ₄ ^3_ source phosphoric acid, a metal phosphate, hydrogen phosphate or dihydrogen phosphate. - - 17. The method according to any one of the preceding claims, characterized in that water is used as a solvent in the precursor mixture. 18. The method according to any one of the preceding claims, characterized in that the Li ⁺ source, the M ²⁺ source are used in the form of aqueous solutions, and the Pθ ₄ ^3- source used in the form of a liquid or an aqueous solution becomes. 19. The method according to any one of the preceding claims, characterized in that the precipitate formed in the Precursorsuspension comprises at least one precursor of L1MPO ₄ , in particular Vivianit, and preferably then carried out under hydrothermal conditions, the reaction in LiMP0 ₄ . 20. The method according to any one of the preceding claims, characterized in that in the hydrothermal conditions. Temperatures between 100 to 250 ° C, in particular 100 to 180 ° C and a pressure of 1 bar to 40 bar, in particular 1 bar to 10 bar vapor pressure can be used. 21. The method according to any one of the preceding claims, characterized in that the components of the precursor mixture in the following stoichiometric ratio are present: a. 1 mol Fe ²⁺ : 1 mol P0 ₄ ^3- : 1 mol Li * (1: 1: 1) b. 1 mol of Fe ²⁺ : 1 mol of P0 ₄ ^{3 ~} : 3 mol of Li * (1: 1: 3) c. every mixing ratio between a and b. 22. The method according to any one of the preceding claims, characterized in that the combination or reaction of the precursor mixture or suspension takes place under hydrothermal conditions under an inert gas atmosphere, preferably in the same vessel. 23. The method according to any one of the preceding claims, characterized in that first in aqueous solvent, the M ²⁺ source and the P0 ₄ ^{3 ~} source, especially under I nertgasatmosphäre, are mixed, then, preferably again under a protective gas or inert atmosphere , the Li ⁺ source is added and then the reaction is carried out under hydrothermal conditions. 24. The method according to any one of the preceding claims, characterized in that it is a treatment with dispersants (with or without pump rotor), Ultraturrax, mills such as colloid mills or Manton-Gaulin mills, intensive mixers, centrifugal pumps, in the dispersing or milling treatment Line mixers, mixing nozzles such as injector nozzles or ultrasonic devices. 25. The method according to any one of the preceding claims, characterized in that the high-shear treatment according to claim lb an agitator or the like, in particular an Ultra-Turrax stirrer is used, wherein the power input, calculated according to the formula P = 2 π n M, where M represents the torque and n the speed is at least 5 kW / m ³ , in particular at least 7 kW / m ³ . 26. The method according to any one of the preceding claims, characterized in that the additional component according to claim 11 or 12 is used as a crystallization seed in the precipitation or reaction of the precursor mixture. 27. LiMP0 ₄ , in particular LiFeP0 ₄ , obtainable according to one of the preceding method claims. 28. L1MPO ₄ , in particular according to claim 27, characterized in that the average particle size (D50 value) at less than 0.8 .mu.m, preferably less than 0.7 .mu.m, in particular less than 0.6 .mu.m, particularly preferred is less than 0.5 microns. 29. LiMP0 according to claim 27 or 28, characterized in that the DIO value of the particles is less than 0.4 μm, preferably less than 0.35 μm, and more preferably the D90 value is less than 3.0 μm, in particular less than 2.5 μm, most preferably less than 2.0 μm. 30. LiMP0 ₄ according to any one of claims 27 to 29, characterized in that the difference between the D90 value and the DIO value of the particles is not more than 2 μm, preferably not more than 1.5 μm, in particular not more than 1 microns, more preferably not more than 0, 5 microns. 31. L1MPO ₄ according to any one of claims 27 to 30, characterized in that that the BET surface area more than 3.5 m ² / g, in particular more than 4 m ² / g, particularly preferably more than 5 m ² / g, more preferably more than 10 m ² / g, most preferably more than 15 m ² / g. 32. Composition, in particular electrode material, containing LiMP0 ₄ according to one of claims 27 to 31. 33. The composition of claim 32, further comprising at least one further component, in particular a carbonaceous or electron-conductive substance or the precursor of an electron-conducting substance, more preferably coal, carbon or carbon fibers. 34. Secondary battery containing a composition, in particular an electrode material according to claim 32 or 33. 35. Use of LiMP0 according to any one of claims 27 to 31 as electrode material. 36 .. The method according to any one of claims 1 to 26, characterized in that after the hydrothermal treatment, the LiMP0 _{4 is} separated, in particular by filtration and / or centrifugation, optionally dried and optionally deagglomerated. 37. The method according to any one of claims 1 to 26, characterized in that the obtained from the Hydrothermalbehandlurig LiMP0 in a pyrolysis process in which at least one carbon precursor material, preferably a carbohydrate such as sugar or cellulose and more preferably lactose, with the LiMP0 _{4 is} mixed, z. B. by kneading, with water can be added as an aid. 38. The method according to claim 37, characterized in that the carbon precursor material is added to the moist LiMP0 ₄ filter cake obtained after the hydrothermal synthesis by separation, the mixture of LiMP0 ₄ and carbon precursor material is dried and heated to a temperature between 500 ° C and 1000 ° C, preferably between 700 ° C and 800 ° C, wherein the carbon precursor material is pyrolyzed to carbon. 39. The method according to claim 38, characterized in that the pyrolysis is followed by a grinding or deagglomeration treatment. 40. The method of claim 38 or 39, characterized in that the drying is preferably carried out on inert gas, in air or in vacuum at temperatures of preferably 50 ° C to 200 ° C, and the pyrolysis is carried out under protective gas.